Uniformity index performance evaluation in an SCR aftertreatment system

ABSTRACT

An exemplary exhaust test tog apparatus includes a housing defining an exhaust flow path extending from an inlet to an outlet. At least a portion of the housing is selectably rotatable relative to an exhaust aftertreatment system. An arm extends from the housing into the exhaust flow path. An exhaust probe configured to measure an exhaust constituent is coupled with the arm and positioned at a location in the exhaust flow path. An actuator is configured to extend and retract the arm to vary the location of the exhaust probe in the exhaust flow path. The exhaust probe is moveable to a plurality of locations within the exhaust flow path through a combination of rotation of the housing and extension and retraction of the arm.

BACKGROUND

The technical field generally relates to aftertreatment control ofemissions in internal combustion engines, and more specifically but notexclusively relates to design and modeling of aftertreatment catalyticsystems.

Selective catalytic reduction (SCR) systems depend upon the injection ofammonia or urea, or sometimes an alternate reductant such ashydrocarbons, into the system. The injected reductant processes in theexhaust gas, ultimately entering the gas phase and adsorbing to thecatalyst surface for reaction with adsorbed NO_(x) from the engine. Thereductant may have to experience evaporation, hydrolysis or otherdecomposition, and adsorption. The resulting exhaust gas composition canbe variable across the exhaust system cross-section, resulting invariability in available reductant and in the ratio of reductant toNO_(x) or other reactants.

SCR systems, and other aftertreatment systems, for mobile applicationssuch as vehicles are highly sensitive to cost and packaging footprint.Catalyst sizing therefore is closely matched to capability, with thesmallest catalyst having the lowest catalyst loadings that will meet theneeds of the application being utilized. The needs of the applicationinclude accounting for part to part variability in manufacturing,degradation over time and events such as high temperature excursions orexposure to sulfur. The uniformity profile of injected and processedreductant is a part of the performance of the aftertreatment system, anddesigns having lower uniformity ultimately require relatively largercatalysts and/or catalyst loadings to meet the requirements of theapplication.

The determination of the uniformity is a challenging operation, and canrequire a large amount of design effort and numerous design iterations.Analytical solutions, such as computational fluid dynamics (CFD)operations allow multiple systems to be tested and adjusted morecheaply, but do not always match real systems. Presently known testingrigs for determining uniformity of exhaust gas constituents, andaccordingly for calibrating a CFD design and/or for testing a physicaldesign, require significant warm-up and preparation periods, allowingfor only a few data point acquisitions each day. Therefore, furthertechnological developments are desirable in this area.

SUMMARY

Unique apparatuses, methods and systems for exhaust aftertreatmentsystem testing are disclosed. One exemplary apparatus includes at leastone exhaust probe being moveable to a plurality of locations within aportion of a sectional area of an exhaust flow path defined in a housingthrough a combination of rotation of the housing and extension andretraction of an arm. One exemplary method includes performing aplurality of measurements of exhaust species concentration with a probein a plurality of locations within a flow path of a test device wherethe probe is moveable to the plurality of locations by operating alinear actuator, rotating at least a portion of the test device, or acombination thereof. One exemplary system is configured to position aprobe in a plurality of locations in an exhaust passage of a test devicethrough movement of an extension member without interrupting exhaustflow in the exhaust passage. Further embodiments, forms, objects,features, advantages, aspects, and benefits shall become apparent fromthe following description and figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 illustrates an exemplary aftertreatment setup in test cell.

FIG. 2 illustrates an exemplary species uniformity measurement system(SUMS).

FIG. 3 illustrates graphs of exemplary grid of locations that may besampled with a SUMS.

FIG. 4 illustrates a map of species across a catalyst face obtainedusing a SUMS.

FIGS. 5-12 illustrate an ammonia to NO_(x) ratio (ANR) distribution forCFD and experimental testing at B50 engine operating conditions.

FIGS. 13-22 illustrate an ANR distribution for CFD and experimentaltesting at C100 engine operating conditions.

FIG. 23 illustrates a graph of experimental ANR uniformity index (UI) vsCFD predicted UI.

FIG. 24 is a graph illustrating an exemplary effect of multipleinjection pulses on CFD predicted ANR UI

FIG. 25 is a graph illustrating an exemplary correlation betweenmeasured ANR UI and CFD predicted ANR UI.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings and specific language will be used to describe the same. Itwill nevertheless be understood that no limitation of the scope of theinvention is thereby intended, any alterations and further modificationsin the illustrated embodiments, and any further applications of theprinciples of the invention as illustrated therein as would normallyoccur to one skilled in the art to which the invention relates arecontemplated herein.

A system is described that is capable of mapping gaseous species acrossthe face of a catalyst under normal engine operating conditions withoutspecial venting mechanisms or substantially changing the flowcharacteristics within the system. This occurs without significantoperator intervention and drastically improves, by several orders ofmagnitude, the time needed to conduct a similar survey from previouslyknown systems.

Current CFD techniques have not adequately captured the complex fluid,heat transfer, and species mechanics necessary to map out the capabilityof a system to spread a reductant evenly. Additionally, current systemscan only sample in predetermined static locations or they must vent intothe atmosphere which can create environmental and health considerations.The described system overcomes one or more of these deficiencies byexperimentally obtaining the necessary information to map out andanalyze these interactions. This capability can then be used, forexample, to design and optimize mixers, inlets, outlets, total systemintegration, and/or test or improve CFD models.

In certain embodiments, all of the parts are designed to be robust tohigh temperatures, or actively cooled, and can accommodate on engineexperimentation for exhaust temperatures up to 575° C. The inclusion ofhigh temperatures parts and/or cooling is optional, and dependent uponthe temperatures of interest for the system. Systems capable ofwithstanding exhaust temperatures higher or lower than 575° C. are alsocontemplated herein.

In certain embodiments, the sampling probes are actively heated oncethey pass out of a sealed area to prevent NH₃, urea, unburnedhydrocarbons, or other gas constituents from sticking to their lines. Anexemplary system includes probe entrances sealed to prevent gases fromventing into the atmosphere. The system includes probes mounted onextension arms which are coupled with linear actuators so thatprogrammable locations can be sampled to increase the radial and/orangular resolution of sampling across the catalyst face. The selectionof tire distance between the probes and the extension length availablefor the actuators allows for rapidly deployable and arbitrarilyselectable configurations of sampling locations. The sampling locationscan be programmed or dynamically calculated based upon the user need,and can be performed through an automated cycle and/or by sequentialpositioning. The positioning may be manually or computer controlled.

With reference to FIG. 1, there is illustrated a system 100 including anexemplary aftertreatment setup in a test cell. System 10D was utilizedin emissions testing performed on a Cummins EPA 2013 ISB 6.7L engine. AnEPA 2013 compliant aftertreatment system was used after the engine tomaintain system backpressure equivalent to an actual system. The exhaustfrom turbine out was passed through a DOC/DPF system 110 including adiesel oxidation catalyst (DOC) 112 and a diesel particulate filter(DPF) 114. The direction of exhaust flow through system 100 is generallyillustrated by arrows 119. System 100 further includes temperaturesensors 116, NO_(x) sensors 117, delta P+P pressure sensors 118, andFourier transform infrared spectroscopy (FTIR) sampling probe 160.

From DOC/DPF system 110, exhaust passes into a decomposition reactortube 120. An aqueous urea solution of diesel exhaust fluid (urea-basedDEF) was dosed in decomposition reactor tube 120 through a doser 122 andconverted into NH₃. The exhaust flow mixed with NH₃ was then passedthrough a hydrolysis catalyst 130 to ensure that all liquid urea wasconverted to NH₃ before the emissions measurement. The SUMS (SpeciesUniformity Measurement System) system 140 was installed after thehydrolysis catalyst 130 to measure the exhaust species concentration.FTIR sampling probes of the SUMS system 140 were connected to an FTIRsystem which provided raw species concentrations. Further details ofSUMS system 140 are described below in connection with FIG. 2.

It shall be appreciated that certain embodiments omit a hydrolysiscatalyst. Such embodiments may inject reductant and allow it to gothrough a shortened selective catalytic reduction before making ameasurement. Rather than measuring NH₃ and HNCO directly, suchembodiments may utilize upstream emissions measurements and emissionsmeasurements of the SUMS to calculate how much reductant was consumed bythe SCR catalyst during NO_(x) conversion and then back calculate howmuch reductant was traveling through a given zone.

An un-catalyzed SCR brick 150 was installed after the SUMS system 140 tomake sure that the back pressure equivalent to an operating system wasobtained. The SCR brick 150 was un-catalyzed to ensure that NO_(x) wasnot reduced by NH₃ before the emissions measurement in the tail-pipe.The size of the SCR brick 150 was determined such that the total volumeof the SCR system (hydrolysis catalyst 130+un-catalyzed SCR brick 150)was equivalent to a production SCR system. An additional FTIR samplingprobe 160 was connected at a sufficient distance downstream of thetailpipe to get a well-mixed measurement of the exhaust species.Periodic leak check and system accuracy tests were performed on the FTIRsystem to ensure quality and integrity of data. Exhaust temperatureswere measured at the locations of temperature sensors 116 in theaftertreatment system illustrated in FIG. 1. The engine and dynamometerwere operated through a scheduled sequence to run the engine at therequired test conditions.

With reference to FIG. 2 there is illustrated an exemplary speciesuniformity measurement system (SUMS) 140. FIG. 2 depicts SUMS 140 in theform of a sampling disk that is configured to be installed in an exhaustsystem at a desired location, for example downstream of a catalyst asillustrated in FIG. 1. The sampling disk of SUMS 140 includes a housing148 which defines an exhaust flow passage 149. The inlet and outlet endsof housing 148 may be coupled with respective first and second portionsof an exhaust aftertreatment system, for example, as illustrated inFIG. 1. SUMS 140 further includes FTIR sampling probes 141 and 142 whichare coupled with extension arms 145 and 146 respectively. Extension arms145 and 146 are operatively coupled with linear actuators 143 and 144,respectively. Linear actuators 143 and 144 are configured to extend andretract extension arms 145 and 146 effective to move probes 141 and 142to different locations across the sectional area of the exhaust flowpassage 149. This movement allows probes 141 and 142 to sample atdifferent locations laterally across the face of an aftertreatmentcomponent with minimal intervention and disruption.

In the configuration illustrated in FIG. 2, probe 141 is illustrated ina nearly fully retracted position and probe 142 is illustrated in anearly fully extended position. SUMS 140 is also rotatable in about itsaxis generally in the direction indicated by arrow 147 which allowsprobes 141 and 142 to sample at different locations circumferentiallyaround face of the SCR brick 150 with minimal intervention anddisruption. A rotation range of at least about 90 degrees in combinationwith the range of the linear actuators 143 and 144 provides effectivesample location coverage of substantially the entire face of the SCRbrick 150. Linear actuators 143 and 144 and rotation of the SUMS 140allow positioning the sampling probe at substantially anycross-sectional location of exhaust flow passage 149 without a shutdownor other interruptions of engine operation. Exemplary sets of testlocations are illustrated in graphs 301 and 302 of FIG. 3 both of whichdepict units of inches on their vertical and horizontal axes.

During the aforementioned linear movement and rotation SUMS 140 canfunction under normal operating engine conditions including duringactive regeneration events. Exhaust gases are prevented from ventinginto the testing space during operation. SUMS 140 can be controlled witha programmable controller to sample across a catalyst face in apredetermined or a dynamic location based upon various inputs. Thedesign of SUMS 140 is easily modified for different size catalysts. SUMS140 can also be instrumented with various tools, includingthermocouples, pressure sensors, hot wire anemometers, to name severalexamples. Using SUMS 140, species may be mapped as a function oflocation which is highly useful information for system design andintegration.

Map 401 illustrated in FIG. 4 was created in two days using the testpoints illustrated in graph 301 of FIG. 3. Map 401 depict units ofinches on its vertical and horizontal axes. Additional radial resolutionwas found to be unnecessary based on the test results, but it can beseen that additional or alternate points and better radial resolution ispossible if desired. Graph 302 of FIG. 3 provides one illustration of analternate set of test points. All points were mapped at three separateengine conditions within the two day period. It is estimated thatconventional test systems would have taken between 54 and 72 days toprovide an equivalent amount of data. Conventional systems requiredthirty minutes per point, then test cell shutdown, an operatoradjustment of the sampling locations, an engine restart, stabilizationto steady state operation, and then re-measurement. Experience withconventional test systems showed that about three to four operatingpoints could be acquired per day.

Description of an example test of a CFD utilizing SUMS 140 in the system100 follows. The system and data taken in the described example providesan example of system and demonstrates the type of data available from,and usage of, the described system. The same or similar tests oroperations are readily performed by one of skill in the art having thebenefit of the present disclosure.

Selective Catalytic Reduction of oxides of nitrogen (NO_(x)) by ammoniahas established itself as an effective diesel aftertreatment technologyto meet stringent NO_(x) emission standards. For satisfactoryperformance, good mixing between reductant and NO_(x) needs to beachieved within tight packaging constraints and typically a uniformityindex (UI) is used to quantify the degree of mixing. A primary objectiveof the disclosed testing was to compare experimentally measured and CFDpredicted uniformity indices in realistic aftertreatment systems and toestablish the correlation between them.

A measurement system, including hardware consistent with the SUMS 140depicted in FIG. 2 was used to measure spatial distributions of ammoniaand NO_(x) at the outlet of a hydrolysis catalyst and to thus derive theexperimental UI. Grid locations for measurement were chosen using theequal area method. In addition, UI was predicted through CFD simulationsusing a multi-component model that accounts for spray processes, watervaporization and urea thermolysis. Synchronized data flow wasestablished between CFD and test-cell to ensure the conditions matchedin both studies. Comparisons were made between experimentally measuredand predicted UIs for 5 different configurations (9 cases), and thecorrelation was established. Main sources of uncertainties inmeasurements and predictions were identified as further described below.

Steady state testing was performed to measure the emissionsconcentrations at different locations across the SCR catalyst face usingthe test cell aftertreatment setup of system 100 including SUMS system140. Tests were conducted at B50 and C100 engine operating conditions.The B50 engine operating condition was selected since it represents thecenter point of the fuel map and is representative of cruising conditionfor an on highway application. The C100 engine operating condition waschosen because it represents a high temperature and high flow condition,which may be a challenging situation from a flow mixing and distributionpoint of view.

Grid points required to map the catalyst face for emissions measurementswere selected based on the equal area method. A total of 48 points werechosen along with the center point. Data at center point was notincluded in the calculation of the uniformity index. The locations ofthe measurement points are illustrated in graph 302 of FIG. 3. Baselineorientation of the SUMS tool mapped the grid in the 0° and 90°directions with regards to the horizontal. The SUMS tool was thenrotated twice by 30° each to map the remaining grid points. The centerpoint was repeated in each orientation.

During the test, initially, both arms of the SUMS tool were pushed outsuch that the probes were at the rim of the catalyst. The engine wasthen controlled to achieve the required exhaust flow conditions. DEFdosing rate was controlled such that ammonia to NO_(x) ratio (ANR) of 1was maintained. Arm 1 of the SUMS tool was then moved to the locationfor point 1 on the grid. Sampling of emissions was started after 10 minrunning to ensure stability. Sample was collected for 5 min at asampling rate of 1 Hz and the average value over 5 min was reported. DEFdosing was shut off at the end of sampling time of 5 min and arm 1 waspushed back out to the rim. The engine was then run at high speed andload conditions for 10 min to acquire high flow rate and high exhausttemperature. This was done to ensure that all residual NH₃ was removedfrom the system before the sample at the next grid location wascollected. After 10 min were complete, the engine was controlled toachieve the required flow rate and temperature conditions (B50 or C100).Then arm 1 was moved to the second grid location. DEF dosing was startedand after 10 min emissions sampling was started. This process wasrepeated for all of the 49 points on the grid. After the grid mappingtest for each configuration was completed, the FTIR sampling probe wasremoved from the SUMS tool and installed in a location downstream oftailpipe out to measure the total average exhaust concentration.

The above mentioned test procedure was performed on five differentconfigurations (9 cases) to develop the correlation between CFDpredicted and experimentally measured UIs. The five configurations (9cases) are outlined in Table 1 below. Eight cases were used to developthe correlation and case 9 was used to validate it.

TABLE 1 Experimental Test Configurations Case SCR Inlet DecompositionOperating # configuration tube condition 1 End Inlet EPA 2010 B50 2 EndInlet EPA 2010 C100 3 End Inlet EPA 2013 B50 4 End Inlet EPA 2013 C100 5Side inlet EPA 2010 B50 6 Side Inlet EPA 2010 C100 7 Side Inlet EPA 2013B50 8 Side Inlet EPA 2013 C100 9 End Inlet with EPA 2013 C100 cyclonemixer

Results and figures from the CFD work and experimental testing areillustrated in FIGS. 5-22. Emissions concentrations measured at each ofthe 49 locations were recorded and cubic interpolation was done to getsurface distribution contour plots. Sufficient ANR distribution acrossthe SCR catalyst face is desirable to achieve maximum NO_(x) conversionefficiency from the SCR catalyst. Hence, ANR distribution across the SCRcatalyst inlet face obtained from CFD is compared to the distributionobtained from experimental testing. The view in FIGS. 5-22 is from theupstream side, or looking at the SCR inlet catalyst face from thedecomposition tube outlet to SCR inlet. It can be seen that data of thetype seen in FIGS. 5-12, which can be taken in a short period of dayswith the described system, can be used to validate a CFD model and/or ahardware design.

FIGS. 5-12 illustrate experimental test results and CFD calculations forB50 operating conditions. FIG. 5 illustrates a graph of CFD calculationresults and FIG. 6 illustrates a graph of experimental test results foran EPA 2010 compliant decomposition tube and SCR end inletconfiguration. FIG. 7 illustrates a graph of CFD calculation results andFIG. 8 illustrates a graph of experimental test results for an EPA 2010compliant decomposition tube and SCR side inlet configuration. FIG. 9illustrates a graph of CFD calculation results and FIG. 10 illustrates agraph of experimental test results for an EPA 2013 compliantdecomposition tube and SCR end inlet configuration. FIG. 11 illustratesa graph of CFD calculation results and FIG. 12 illustrates a graph ofexperimental test results for an EPA 2013 compliant decomposition tubeand SCR side inlet configuration.

FIGS. 13-22 illustrate comparisons of experimental test results and CFDcalculations for C100 operating conditions. FIG. 13 illustrates a graphof CFD calculation results and FIG. 14 illustrates a graph ofexperimental test results for an EPA 2010 compliant decomposition tubeand SCR end inlet configuration. FIG. 15 illustrates a graph of CFDcalculation results and FIG. 16 illustrates a graph of experimental testresults for an EPA 2010 compliant decomposition tube and SCR side inletconfiguration. FIG. 17 illustrates a graph of CFD calculation resultsand FIG. 18 illustrates a graph of experimental test results for an EPA2013 compliant decomposition tube and SCR end inlet configuration. FIG.19 illustrates a graph of CFD calculation results and FIG. 20illustrates a graph of experimental test results for an EPA 2013compliant decomposition tube and SCR side inlet configuration. FIG. 21illustrates a graph of CFD calculation results and FIG. 22 illustrates agraph of experimental test results for an EPA 2013 compliantdecomposition tube and SCR end inlet configuration with a cyclone mixer.

It can be observed from FIGS. 5-22 that, for both the B50 and C100engine operating conditions and the different aftertreatment systemconfigurations, the ANR distribution contours obtained from CFD and fromexperimental testing are visually similar. Decomposition tube clockingwith respect to vertical has significant influence on the ANRdistribution across the SCR catalyst face in case of the end inletconfiguration. During the experimental testing, the decomposition tubewas clocked at 45° in the clockwise direction when viewed from decompinlet side to outlet. It was ensured that similar orientation wasincorporated in the model used for CFD work. Thus, we can see that forthe end inlet configuration without cyclone mixer, majority of ANR isconcentrated in the top right corner as shown by plots from CFD as wellas experimental testing.

For the side inlet configurations, it can be seen from the figures thatthe ANR distribution across the catalyst face is much more uniform.Presence of elbows in the side inlet configurations causes turbulenceand better mixing of NO_(x) and NH₃ resulting in better ANRdistribution. As mentioned above, this uniform distribution is capturedboth in CFD and experimental testing.

Species distribution data shown above was used to calculate the speciesdistribution uniformity indices from both CFD and experimental testing.The details of the CFD, and the specific results of the various hardwareconfigurations tested, are not limiting of the disclosures herein. Thesystem described herein can be utilized to test any CFD and/or hardwareconfiguration.

Equations 2 shown below were used to calculate a uniformity index (UI)from experimental data, and provides one example of how the system canbe utilized to provide a UI. The emissions measurement in the downstreamat tail pipe out was used for the average value in the denominator inthe equation below.

$\begin{matrix}{{{\gamma_{L\; 1} = {1 - {\frac{1}{2}\left( {\sum\limits_{i = 1}^{n}\;{\frac{A_{i}}{A_{tot}}\frac{{v_{i} - v_{avg}}}{v_{avg}}}} \right)}}},{where}}{v_{avg} = \left( {\sum\limits_{i = 1}^{n}\;\frac{A_{i}v_{i}}{A_{{tot}\;}}} \right)}{A_{tot} = {\left( {\sum\limits_{i = 1}^{n}\; A_{i}} \right).}}} & {{Equations}\mspace{14mu} 2}\end{matrix}$

As mentioned before, since ANR distribution across the SCR catalyst facehas significant influence on NO_(x) conversion performance of thecatalyst, ANR UI was calculated using the above mentioned equations andis shown in the subsequent plots.

FIG. 23 illustrates ANR UI calculated from experimental measurementsplotted against ANR UI predicted from CFD. FIG. 23 illustrates measuredANR UI on its vertical axis and CFD ANR UI on its horizontal axis. FIG.23 depicts ANR UI points 701, a line of perfect correlation 710, a +12%deviation line 720, and a −12% deviation line 730. Data of the typeshown in FIG. 23 can be utilized to quantify the quality of a CFD model.It can be observed that the measured ANR UI is greater than the CFDpredicted UI for all the points. Thus is because localized higherconcentration patches observed at the periphery in the distributionplots from CFD cause a drop in UI value. The experimental hardware wasnot utilized to measure close to the periphery of the catalyst. Themaximum error between the measured ANR UI and CFD predicted ANR UI wascalculated and is shown in the figure with black lines. The measured ANRUI is within ±12% agreement with the CFD predicted ANR UI. In theexample, the 12% error band is acceptable considering the differencesbetween the CFD analysis and experimental testing which are outlinedbelow. One of skill in the art will understand an acceptable error bandfor a given application having the benefit of the disclosures herein.

Some differences between the CFD analysis and the experimental testingin the example having data depicted in FIG. 23 include:

(1) Experimental data was collected after five minutes of running at aparticular grid location. Thus was the time required for the conditionsand emissions to stabilize before data could be sampled. The total inntime for the test for one configuration was forty eight hours. On thecontrary CFD simulation data was obtained from one injection pulse whichwas for duration of one second.

(2) Experimentally measured UI was calculated from emissionsmeasurements at forty eight points. The CFD model contains a mesh ofapproximately 4000 cells and data from all of them is used to calculatethe CFD predicted UI.

(3) Emissions measurement was not performed in the experimental setupwithin the peripheral area (˜16.5%) of the catalyst and hence was notused in calculation of experimentally measured UI. CFD predicted UIcalculation throughout the entire area of the catalyst face.

To understand the effect of the first difference, multiple injectionspulses were simulated for one of the configurations and CFD predicted UIwas calculated from the same and is shown in the graph of FIG. 24 whichillustrates an ANR index on its vertical axis and rime in seconds on itshorizontal axis. It can be observed that there is a slight increase inUI when multiple injection pulses are simulated. Extent of change willbe dependent on configuration and test conditions. The change will besmall when the percentage evaporation of urea is high.

In the test operations, data from eight of the nine data pointscollected from the different configurations were used to develop acorrelation between experimentally measured ANR UI and CFD predicted ANRUI. The data point from the EPA 2013 end inlet configuration withcyclone mixer was used to validate the correlation. The correspondingplot is shown in FIG. 25. The results of the particular correlation testare not important, but it can be seen that the system can be used togenerate data such as that depicted in FIG. 25 to calibrate or verify aCFD model for the system.

Measured ANR UI calculated from the equation is plotted along with theexperimentally measured ANR UI for the EPA 2013 end inlet with cyclonemixer configuration. The graph of FIG. 25 illustrates measured ANR UI onits vertical axis and CFD predicted ANR UI on its horizontal axis.Points 910 are eight ANR UI measurement points. Point 920 is a measuredANR UI for an EPA 2013 compliant SCR end inlet configuration with acyclone mixer at C100 engine operating conditions. Point 930 is anequation predicted ANR UI for an EPA 2013 compliant SCR end inletconfiguration with a cyclone mixer at C100 engine operating conditions.The correlation equation of the line illustrated in FIG. 25 isy=0.7808x+0.2298 and R²=0.9484. FIG. 25 also illustrates an error bar940 encapsulating the ±12% error shown in FIG. 23 and it can be observedthat the experimentally measured ANR UI falls within the errors bars.Thus, it can be concluded that the equation is valid for the purposes ofthe system tested in FIG. 25. The error bar 940 and determinations ofvalidity are selectable according to the needs of the user for aparticular system.

A number of exemplary embodiments will now be further described. Oneexemplary embodiment includes a sampling disk comprising an outerhousing comprising a diameter of a target aftertreatment systemcomponent, a sampling probe having a sampling tip and an extension,wherein the extension is at least one-half diameter of the outerhousing, and two linear actuators operationally coupled to the extensionand structured to position the sampling tip at any cross-sectionalposition within the outer housing. The present exemplary embodiment mayinclude one or more the following features. The extension may sealablypass through the outer housing. The outer housing may be rotatable.Rotation of the outer housing may change an angle of linear actuation ofthe extension in response to the linear actuators, and the angle changemay be relative to an aftertreatment component. The aftertreatmentcomponent comprises at least one component selected from the componentsconsisting of: an oxidation catalyst, a particulate filter, a catalyzedparticulate filter, a decomposition tube, a hydrolysis catalyst, aselective reduction catalyst, a turbocharger outlet, and a portion of anexhaust pipe.

Another exemplary embodiment is a method utilizing a system according tothe preceding exemplary embodiment. The method includes determining atleast one exhaust gas composition constituent at a plurality ofcross-sectional points to determine a distribution of the exhaust gascomposition constituent. The present exemplary embodiment may includeone or more the following features. The method may include determiningthe plurality of cross-sectional points in response to an equal areamethod. The method may include determining at a number of the pluralityof cross-sectional points within a single day, the number comprising anumber greater than five, greater than ten, greater than twenty-five,and/or greater than forty. The method may include performing thedetermining at a plurality of engine operating conditions. The pluralityof engine operating conditions may include a B50 point and a C100 point.The method may include verifying a CFD model in response to thedetermining. The method may include verifying a hardware design inresponse to the determining and/or the verifying. The exhaust gascomposition constituent may include a constituent that can be correlatedto a reductant distribution. The exhaust gas composition constituent maycomprise a constituent that can be correlated to a localizedreductant:NO_(x) ratio.

A further exemplary embodiment is an exhaust testing apparatus. Theapparatus includes a housing defining an exhaust flow path extendingfrom a housing inlet to a housing outlet, the housing inlet and thehousing outlet configured to connect with respective first and secondportions of an exhaust aftertreatment system, at least a portion of thehousing being selectably rotatable relative to at least one of the firstand second portions of the exhaust aftertreatment system. The apparatusfurther includes an arm extending from the housing into the exhaust flowpath, an exhaust probe coupled with the arm and positioned at a locationin the exhaust flow path, the exhaust probe configured to measure anexhaust constituent, and an actuator configured to extend and retractthe arm to vary the location of the exhaust probe in the exhaust flowpath. The exhaust probe is moveable to a plurality of locations within aportion of a sectional area of the exhaust flow path through acombination of rotation of the housing and extension and retraction ofthe arm. The present exemplary embodiment may further include theexhaust aftertreatment system which may include a first aftertreatmentcomponent positioned upstream from the housing inlet, a secondaftertreatment component positioned downstream from the housing outlet,and an injector positioned upstream from the first aftertreatmentcomponent. The first aftertreatment component may be a hydrolysiscatalyst, the second aftertreatment component may be an SCR brick, andthe injector may be coupled with a supply of aqueous urea solution. Incertain forms the probe comprises an FTIR probe configured to measureexhaust species concentration. In certain forms the sectional areacomprises about 50% or more of the total sectional area of the exhaustflow path. In certain forms the plurality of positions comprisesubstantially all positions within the sectional area. In certain formsthe apparatus further includes a second arm extending from the housinginto the exhaust flow path, a second exhaust probe coupled with thesecond arm and positioned at a second location in the exhaust flow path,the second exhaust probe configured to measure exhaust speciesconcentration, and a second actuator configured to extend and retractthe second arm effective to vary the location of the second exhaustprobe within the exhaust flow path. The second exhaust probe is moveableto a second plurality of locations within a second portion of a secondsectional area of the exhaust flow path through a combination ofrotation of the housing and extension and retraction of the second arm.In certain forms the sectional area and the second sectional area eachcomprises about 50% the total sectional area of the exhaust flow path.

Another exemplary embodiment is a system including ah exhaustaftertreatment system configured to receive exhaust from an internalcombustion engine and a test device operatively coupled with the exhaustaftertreatment system, the test device including an exhaust passageconfigured to receive exhaust from the exhaust aftertreatment system, anextension member extending into the exhaust passage, a probe coupledwith the extension member and configured to measure a constituent of theexhaust, and an actuator configured to move the extension member. Thesystem is configurable to position the probe in a plurality of locationsin the exhaust passage through movement of the extension member withoutinterrupting exhaust flow in the exhaust passage. In certain forms thetest device further includes a second extension member extending intothe exhaust passage, a second probe coupled with the second extensionmember and configured to measure a constituent of the exhaust, and asecond actuator configured to move the second extension member, whereinthe system is configurable to position the second probe in a secondplurality of locations in the exhaust passage through movement of thesecond extension member without interrupting exhaust flow in the exhaustpassage. In certain forms the plurality of locations of the probeintersect a line extending through a center point of the exhaust passageand the second plurality of locations of the second probe intersect asecond line extending through the center point. In certain forms thesystem is configurable to measure a constituent of the exhaust with oneof the first probe and the second probe at substantially any location ina sectional area of the exhaust passage through a combination of linearmovement of the extension member, linear movement of the secondextension member, and rotation of the extension member and the secondextension member relative to the exhaust flow passage. In certain formsthe linear movement and the rotation of the extension member areeffective to position the first probe in substantially any position in afirst 50% of the sectional area of the exhaust passage and the linearmovement and the rotation of the second extension member are effectiveto position the second probe in substantially any position in a second50% of the sectional area of the exhaust passage. In certain forms theextension member and the second extension member are rotatable by atleast 90 degrees relative to the exhaust aftertreatment system.

It shall be appreciated that the number and spacing of positions thatcomprise substantially all positions within a given sectional areadepend upon system-specific parameters that would be appreciated by oneof skill in the art contemplating a specific system. One example ofsubstantially all positions includes spacing of the positions such thata gradient of interest is lower than a threshold value between anyadjacent positions, where the gradient may be a composition,temperature, flow rate, and/or material phase (e.g. vapor versus liquidphase) difference. Another example of substantially all positionsincludes spacing of the positions such that each measurement positioncovers less than a threshold cross-section of the overall flow area,which threshold cross-section includes a selected value depending uponthe application, and which may include not greater than 1 cm², notgreater than 5 cm², not greater than 10 cm², and/or not greater than 25cm², but may include other area values. Yet another example ofsubstantially all measurements includes sufficient coverage ofmeasurements such that uncovered areas are either too small to be ofconcern, or that are not of concern for other reasons—for example whereface plugging on a catalyst is known to occur within a certain region onthe catalyst, an area where face plugging is not a concern may not becovered by a measurement and yet substantially all positions within asectional area may be measured.

It shall be appreciated that a measurement covering a position indicatesthat the measurement is a measurement within a given area that is in aposition expected to be descriptive of a given area. Intentionalmeasurement redundancy, for example, may provide for multiplemeasurements within a given area, where a measurement neverthelesscovers that area. The area covered by the measurements may be the sameor distinct between measurements. It shall be further appreciated that,depending upon the specific system being contemplated, the informationrelevant to determining substantially all positions may include the celldensity of a component, the flow rates in the measurement area, thetemperatures and/or heat transfer environment in the measurement area,the expected issues in the system due to non-uniformily ofaftertreatment flow, the catalyst loading and distribution geometry ofcatalyst within a component, the gradients expected in a system, and/orthe gradients that are acceptable in the system. It shall be appreciatedthat one of skill in the art, having information relevant to aparticular system, and having the benefit of the disclosures herein, canreadily determine a plurality of positions that comprise substantiallyall positions within the sectional area.

An additional exemplary embodiment is a method including connecting atest device to an exhaust aftertreatment system, the test devicecomprising an exhaust flow path, a support extending into the exhaustflow path, a probe coupled with the support, and an actuator configuredto move the support. The method further includes operating an engine tooutput exhaust to the exhaust aftertreatment system, performing a firstexhaust measurement with the probe in a first location in the exhaustflow path, operating the actuator to move the probe to a second locationin the exhaust flow path, performing a second exhaust measurement withthe probe in the second location, rotating at least a portion of thetest device to move the probe to a third location in the exhaust flowpath, and performing a third exhaust measurement with the probe in thethird location. In certain forms the method further includes determininga distribution of at least one exhaust gas constituent based at least inpart upon the first exhaust measurement, the second exhaust measurement,and the third exhaust measurement. In certain forms the method furtherincludes repeating said operating the actuator and said rotating atleast a portion of the test device a plurality of times effective toposition the probe at a plurality of locations within a portion of asectional area of the exhaust flow path in addition to the firstlocation, the second location, and the third location, and performing aplurality of measurements of exhaust species concentration with theprobe in each of the plurality of locations. In certain forms theplurality of locations are selected based upon an equal area method. Incertain forms the method further includes correlating the distributionof the exhaust gas composition constituent to at least one of areductant distribution and a localized ratio of reductant to NO_(x). Incertain forms the method further includes verifying a CFD model basedupon the determining. In certain forms the method further includesverifying a hardware design in response to at least one of thedetermining and the verifying.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly certain exemplary embodiments have been shown and described. Thoseskilled in the art will appreciate that many modifications are possiblein the example embodiments without materially departing from thisinvention. Accordingly, all such modifications are intended to beincluded within the scope of this disclosure as defined in the followingclaims.

In reading the claims, it is intended that when words such as “a,” “an,”“at least one,” or “at least one portion” are used there is no intentionto limit the claim to only one item unless specifically stated to thecontrary in the claim. When the language “at least a portion” and/or “aportion” is used the item can include a portion and/or the entire itemunless specifically stated to the contrary.

The invention claimed is:
 1. A method comprising: receiving exhaust intoan exhaust passage of a test device operatively coupled to an exhaustaftertreatment system; positioning a first probe of the test device in afirst plurality of locations in a first portion of a sectional area ofthe exhaust passage for measuring a constituent of the exhaust flowingthrough the exhaust passage, wherein positioning the first probecomprises moving a first extension member coupled to the first probebetween (i) a first retracted position, in which the first probe islocated adjacent to an inner surface of a housing of the test device,and (ii) a first extended position, in which the first probe is locatedat a position beyond a central axis of the housing; and positioning asecond probe of the test device in a second plurality of locations in asecond portion of the sectional area of the exhaust passage formeasuring the constituent of the exhaust flowing through the exhaustpassage, wherein positioning the second probe comprises moving a secondextension member coupled to the second probe between (i) a secondretracted position, in which the second probe is located adjacent to theinner surface of the housing, and (ii) a second extended position, inwhich the second probe is located at the position beyond the centralaxis of the housing.
 2. The method of claim 1, further comprisingrotating the housing of the test device for positioning the first probein the first plurality of locations.
 3. The method of claim 1, furthercomprising rotating the housing of the test device for positioning thesecond probe in the second plurality of locations.
 4. The method ofclaim 1 further comprising determining a distribution of the constituentin the exhaust based upon measurements from the first probe and thesecond probe.
 5. The method of claim 1 further comprising determining acorrelation of the distribution of the constituent to at least one of areductant distribution and a localized ratio of reductant to NO_(x). 6.The method of claim 1, further comprising measuring the constituentbased upon the measurements obtained through a combination of linearmovement of the first extension member, linear movement of the secondextension member, and rotation of the housing.
 7. The method of claim 1,wherein the first plurality of locations comprises substantially anylocation in a first 50% of the sectional area of the exhaust passage,and the second plurality of locations comprises substantially anylocation in a second 50% of the sectional area of the exhaust passage.8. The method of claim 1 wherein the first plurality of locations andthe second plurality of locations are selected based upon an equal areamethod.
 9. The method of claim 1, wherein the first plurality oflocations of the first probe intersect a line extending through a centerpoint of the exhaust passage and the second plurality of locations ofthe second probe intersect a second line extending through the centerpoint.
 10. The method of claim 1, wherein moving the first extensionmember comprises moving the first extension member between (i) the firstretracted position, in which the first probe is located adjacent to theinner surface of the housing at a first side of the housing, and (ii)the first extended position, in which the first probe is locatedadjacent to the inner surface of the housing at a second side of thehousing, opposite the first side.
 11. The method of claim 1, whereinmoving the second extension member comprises moving the second extensionmember between (i) the second retracted position, in which the secondprobe is located adjacent to the inner surface of the housing at a firstside of the housing, and (ii) the second extended position, in which thesecond probe is located adjacent to the inner surface of the housing ata second side of the housing, opposite the first side.
 12. The method ofclaim 1, wherein the sectional area comprises about 50% or more of atotal sectional area of the exhaust passage.
 13. The method of claim 1,wherein the sectional area comprises about 100% of a total sectionalarea of the exhaust passage.
 14. The method of claim 1, wherein each ofthe first probe and the second probe is an FTIR probe.
 15. The method ofclaim 1, wherein the first portion of the sectional area and the secondportion of the sectional area each comprises about 50% of a totalsectional area of the exhaust passage.